Give us a links to a couple of the songs you're trying to download.
Just FYI, the "stock" browser is the one that came with our phone, e.g., "Internet." There are other browsers you can download from the play store, like Chrome, Firefox and Dolphin. These are "aftermarket" or "3rd party" browsers. DRM stands for Digital Rights Management, which is a form of copy protection. For example, until a few years ago, all the music on iTunes had DRM, and you could only download and play the songs on iTunes or an iPod.
I suspect I know the answer, but I can be sure if I can check the links.